Multicast fails before bandwidth starts becoming an issue. Collisions and congestion are fact of life and do not necessarily mean that links are full (you may j

Multicast fails before bandwidth starts becoming an issue. Collisions and congestion are fact of life and do not necessarily mean that links are full (you may just have lots of packets stuck close together in time). Most TCP implementations handles it well and Linux has well written guides on how to tune parameters when the defaults don't match well to your specific situation well. Multicast just fails catastrophically in arcane ways that depend upon your specific hardware, network topology and mix of your firmware version on your switch/routers. It makes it very hard to "design" a product around that kind of fragile system.